474 BOTAXICAL GAZETTE [june 



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EXPLANATION OF PLATES XXVIII-XXX 



All figures were drawn with the aid of a Spencer camera lucida with Bausch 

 and Lomb ,'j immersion and ocular 12, except figs. 1-11 inclusive, which 

 were drawn with Bausch and Lomb A immersion and ocular 12. Magni- 

 fication of figs, i-n inclusive X3500; all others X 2650. The plates are 

 reduced to two-thirds the original size. 



PLATE XXYUI 



Fig. 1. — Late telophase of the last division of the sporogenous tissue, 

 showing the anastomoses and the beginning of vacuolization along the median 

 longitudinal axis. 



Fig. 2. — A later stage, most of the chromosomes being vacuolate. 



Figs. 3, 4. — Early stages of the pollen mother cells, which consist of 

 ladder-like structures that arose by vacuolization of the chromosomes; some 

 of the chromosomes still entire, owing to unevenness of vacuolization. 



